‘‘We are very pleased to have played a pivotal role in returning Mongolia’s million-dollar baby,’’ US Attorney Preet Bharara said. ‘‘Of course, that million-dollar price tag, as high as it is, doesn’t begin to describe the true value of an ancient artifact­ that is part of the fabric of a country’s natural history and cultural heritage.’’

The skeleton had been looted from Mongolia’s Gobi Desert and smuggled into the United States by fossils dealer Eric Prokopi, authorities said. Prokopi, who bought and sold whole and partial dinosaur skeletons out of his Florida home, illegally imported the bones then assembled them, authorities said.

The dinosaur was seized by Immigration and Customs Enforcement agents after it was sold at auction in New York for over $1 million last year. The government said the skeleton was mislabeled as reptile bones from Great Britain.

By law, any dinosaur fossils found in Mongolia belong to the country and its people.

‘‘It’s really important that as nations we recognize there’s a difference between art sold in the regular course of business, and then there are things that are truly national heritage,’’ said ICE’s director, John Morton.

Prokopi, of Gainesville, Fla., pleaded guilty in December to conspiracy, fraudulent transfer of the bones, and making false statements to authorities.

Mongolia’s president, Tsakhia Elbegdorj, has thanked US authorities for returning the dinosaur, which once stood 8 feet tall and was 24 feet long. It will eventually be displayed at the new Central Dinosaur Museum of Mongolia.